[1] Childrens Hosp Philadelphia, Div Infect Dis, Philadelphia, PA 19104 USA
[2] Univ Penn, Sch Med, Dept Pediat, Philadelphia, PA 19104 USA
[3] Univ Penn, Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[4] Aristotle Univ Thessaloniki, Dept Pediat 3, GR-54006 Thessaloniki, Greece
[5] NCI, Pediat Oncol Branch, Bethesda, MD 20892 USA
[6] Natl Yang Ming Univ, Taipei 112, Taiwan